PROJECT SUMMARY Although smoking rates in the US have decreased, the recent declines in cigarette sales are offset by sharp increases in the consumption of other tobacco products including vaping products or electronic nicotine delivery systems (ENDS). In fact, the prevalence of electronic cigarette use and vaping among youth and young adults (YYA) now exceeds that of combustible cigarettes. One of the reasons behind the rapid increase in YYA e-cigarette use is the extensive and effective marketing of these products. These products are increasingly aggressively marketed on digital and social media, which are disproportionately popular among this hard-to-reach at-risk age group. Thus, social media interventions to prevent e-cigarette use are necessary but have unknown potential effects in a competitive communication environment characterized by an influx of ENDS product marketing and advocacy, potentially resulting in audience confusion and misinformation. Therefore, measuring the social media engagement with the e-cigarette use prevention campaigns would represent an important advancement to the science of prevention and lend evidential support for tobacco regulatory policy. The proposed research aims to inform our understanding of the amount, content, sources, and engagement of Twitter messages related to recent prevention campaigns discouraging e-cigarette use. We will analyze Twitter conversations about 14 state campaigns and one national campaign??The Real Cost? youth e-cigarette use prevention campaign launched by the Food and Drug Administration (FDA). Specifically, we propose to analyze Twitter content related to these campaigns to help inform the health organizations and the general public about the amount of campaign-related messaging, reach and engagement by campaign (Aim 1); the sources of the messages and the themes of the supportive and oppositional content related to tobacco control regulatory policy and prevention science, including misinformation, health claims, flavors and policy on Twitter (Aim 2). This innovative proposal builds on Social Data Collaboratory?s programming and analytic infrastructure and social media data analysis expertise. This research is directly responsive to the National Cancer Institute?s Tobacco Control Research Priorities for the Next Decade. Effective communication strategies regarding harmful and potentially harmful constituents and risks of tobacco products. Fulfillment of the aims will build a scientific base for potential prevention interventions on social media, as well as the programming infrastructure for surveillance and active engagement with user-generated tobacco-related content on Twitter. Results of the study will serve as a foundation for an R01 application characterizing the content, sources, and diffusion patterns of messages related to counter-marketing of non-combustible products on social media and influence of such messages on individual knowledge, attitudes and behavior in a representative sample of youth and young adults.